11 November 2006

Sudoku Tips

Sudoku Tips from sudoku.org.uk: 
This tip comes from Telegraph solver David Brook:

I think my tip might help solvers a lot. It is a little laborious the first time, but the gains are enormous. The Impossible Diabolical in the Sudoku Experiment took me about 2.5hrs utilising my method. My tip is to set out nine grids using blank worksheets. Allocate one grid to each of the values 1 to 9 and work from there. Eg, say the given starting grid contains a 5 at grid point 2,3, then working on the new “5” grid one can blank out all of row 2 and all of column 3 and all of square 1. Then you can blank out the 2,3 grid point on the other 8 grids. Proceed in this way for all the given data and the subsequent steps in the solution become much easier to see - and the ‘what if’ thoughts easier to remember.

10 November 2006

Sudoku Tips

Sudoku Tips from sudoku.org.uk: 
Further to John MacLeods useful tips, I too use an Excel grid, (see first spreadsheet below) but colour fill the cells. The given numbers have bright yellow fill and then all numbers derived from the given numbers have a paler yellow fill. When it comes to a decision point in the “Tough” and “Diabolical” puzzles , then copy the grid within the spreadsheet and use another colour, that way you can then get back to your decision point if that particular option/decision was incorrect.

Now after a few weeks since the Sudoku puzzles first appeared, I only have to resort to the spreadsheet for Tough and Diabolical puzzles to determine the solution.

Further to Malcolm Sevren’s comments about “showing the logic track that was used to complete the grid” the second spreadsheet below shows where the cells have 2 numbers in them; the 1st larger font size number being the solution and the 2nd smaller font size number being the sequence of derivation… I guess the down side is that it would take up too much space in the paper to be legible.